Rhizospheric bacteria are soil bacteria inhabiting the near-root zone, with multifarious activities including the promotion of plant growth, nutrient mobilization, and biological control of pests and diseases. Rhizobacteria produce microbial volatile organic compounds (mVOCs) that can be utilized as biocontrol components against phytopathogenic fungi. Here, we analyzed the mVOCs produced from cotton rhizobacteria and their role in biological control of the fungus Macrophomina phaseolina. Twelve endospore-forming rhizobacterial strains were isolated from the cotton rhizosphere and screened for their biocontrol potential. Three rhizobacterial strains, Bacillus cereus CICR-D3, Bacillus aryabhattai CICR-D5 and Bacillus tequilensis CICR-H3 were evaluated for mVOCs using gas chromatography-mass spectrometry (GC-MS). Major antifungal mVOCs i.e. Benzene, 1, 3-diethyl- and Benzene, 1, 4-diethyl followed by naphthalene, m-ethylacetophenone and ethanone, 1-(4-ethylphenyl) were produced by these strains. The relative abundance of mVOCs released was highest from CICR-D3 followed by CICR-D5 and CICR-H3. Bi-compartmental Petri plate assay against Modiolula phaseolina showed that the CICR-D3 strain was the most effective in inhibiting the mycelial growth (86.70 ± 0.50%), followed by the CICR-D5 (69.27 ± 0.17%) and CICR-H3 (62.84 ± 0.50%) strains. Furthermore, in vivo co-inoculation in a polyhouse revealed that severity of root rot caused by M. phaseolina was reduced by 72.74% in potted cotton plants inoculated with CICR-D3 strain, followed by strains CICR-D5 (69.04%) and CICR-H3 (66.60%). To the best of our knowledge, the specific volatiles are being reported for the first time from native cotton rhizobacterial strains, which provides new insight into cotton rhizobacteria and their antifungal mVOCs as an eco-compatible strategy for cotton root rot management.

根际细菌是栖息在近根区的土壤细菌，具有促进植物生长、养分动员和病虫害生物防治等多种活动。根际细菌产生的微生物挥发性有机化合物 (mVOC) 可用作对抗植物病原真菌的生物防治成分。在这里，我们分析了棉花根际细菌产生的 mVOCs 及其在真菌 Macrophomina phaseolina 生物控制中的作用。从棉花根际分离出 12 株形成内生孢子的根际菌株，并筛选其生物防治潜力。三种根际菌株，蜡状芽孢杆菌CICR-D3、Bacillus aryabhattai CICR-D5 和Bacillus tequilensis使用气相色谱-质谱 (GC-MS) 评估 CICR-H3 的 mVOC。主要的抗真菌mVOCs 即苯，1, 3-二乙基-和苯，1, 4-二乙基，其次是萘，间-乙基苯乙酮和乙酮，1-(4-乙基苯基)。CICR-D3释放的mVOCs的相对丰度最高，其次是CICR-D5和CICR-H3。双室培养皿试验表明，CICR-D3 菌株抑制菌丝生长最有效（86.70 ± 0.50%），其次是 CICR-D5（69.27 ± 0.17%）和 CICR-H3（62.84 ± 0.50%) 应变。此外，在 polyhouse 中的体内联合接种表明，由M. phaseolina 引起的根腐病的严重程度在接种 CICR-D3 菌株的盆栽棉花植物中降低了 72.74%，其次是菌株 CICR-D5 (69.04%) 和 CICR-H3 (66.60%)。据我们所知，首次报道了天然棉花根际菌株的特定挥发物，这为棉花根际细菌及其抗真菌 mVOCs 作为棉花根腐病管理的生态相容策略提供了新的见解。